How to Fix a Surging Lawn Mower

hi guys buck wsr weezer here putting the dew in to do it yourself and i got an mtd mower here with a honda engine and it starts up fine and runs okay for a couple of minutes but when it heats up when it warms up starts surging like crazy runs poorly and it's really intolerable our job today is to figure out how to fix it it just does that surging and hunting constantly and uh i want to talk to you about why it's doing that and it's related to fuel flow through the carburetor i want to take down the air cleaner and just show you you know when we start this guy up cold it runs fine for a few minutes it's equipped with an automatic choke and you may not be able to see it but in there there's a choke plate that when the engine's cold that's in the closed position but as it warms up that plate opens and it's completely open now as is proper that's what it's supposed to be um but when it opens we get full air flow through the carburetor but we're not getting enough fuel flow up from the through the main jet of the carburetor so it's running yeah they're not happy about it either yeah it's running too lean getting more air and not enough fuel and that's why it surges and hunts and goes up and down intolerably what we're going to do today is try to clean out that carburetor and main jet and hope we can get some better fuel flow through that carburetor we'll put it up on the workbench and take it down and clean it out the the fuel has just gummed it up and uh happens a lot so let's see if we can fix it so first thing we're going to shut off the fuel flow with this valve that's fortunate to have a shut off valve there open up the air cleaner assembly and remove the cover and the filter now we got these two 10 millimeter bolts that hold it all up in place so these guys have to come out i carry around this 10 millimeter nut driver just never use it very much let's use it now [Applause] so on these bolts it holds up the carburetor the air cleaner assembly the variety of gaskets and spacers and it's not a big deal taking it off it's just getting it back on that is sometimes the challenge because the cover obstructs your ability to make connections and stuff so start stuff starting to fall those bolts come down all right so this cover connected to this cover is the breather two from the crankcase so you can unplug that move him out of the way so you see the carburetor's all ready falling down here's the gasket from the front then the carburetor and this big gasket the uh choke mechanism here hopefully it won't be too bad putting it back up this gasket is still up there and we'll just leave him on there to make our lives a little easier give you a little closer view of what we're doing here we have to disconnect the fuel line and then this linkage at the top of the throttle plate and then the carburetor's off so not too bad i guess i gotta get some pliers to take that off there we go you may get a little spillage so i got a rag line comes off and i do the linkages last because you've got to be able to twist the carburetor side to side and all to get those linkages off so there's the thin wire it's pretty easy to get off and then this guy all right not too bad so there's the carburetor he's completely off and we're going to clean him off on the outside and then take him apart and take do a thorough cleaning on the inside so there's still fuel in this bowl so now we're gonna be now we can take off this uh bowl with a 10 millimeter wrench or ratchet or whatever you got and we should get some gas coming out the bottom here that's why i got my rag so don't lose that bolt there and bowl looks clean i don't see any i don't see any residue or gunk in there but up through there is the main jet and that's what we want to try to get out with a small screwdriver hopefully and be able to clean that out thoroughly well cleaning out this carburetor is never uh it's never an easy thing to film or show but i'm going to give you my best shot at it i'm going to remove the float by pulling out this pin so here's the float with the needle just move that aside now if you can see down into the through here you probably can't there's the main jet that can be on can come out with a screwdriver and sometimes those are stuck and really hard to get out also finding the right size screwdriver that actually fit down in there can be a challenge i think i got it so we get the main the the jet here and the tube and these are what we want to thoroughly clean they're fine passageways through which fuel has to flow we want to try to clean those out as best we can in addition we just want to use some carburetor cleaner and clean out all the all the spots on here all the crevices nooks crannies all the different places where we can thoroughly clean this out but the main things that we want to make sure get de-gummed are these so with the variety of fine uh brushes and picks and wires we try to clean these out as there is thoroughly as we can to wash away and uh and clean off any fuel residue or gum or varnish that builds up in those things over time another thing we want to clean out is we want to remove this phillips head screw that guy was really tight to loosen but i got it and we want to clean out that low speed jet through here with some carburetor spray i put the tip of the needle through these small holes to make sure they're not obstructed all the way around some of them are very small well all of them are some are bigger than others but i got some fine brushes we can use to clean out in there you know they're just very fine passages so if they get slightly gummed up you know slightly gummed up is significant when you're talking about passages that are this small to begin with with the carb spray and small tools and brushes and do our best to clean it as best we can and then we'll be ready to put it back together see if we made any progress all right let's try to get this carburetor back up and keep our fingers crossed that it's going to work now i've laid out the parts in the order in which they have to go up here air cleaner gasket carburetor gasket choke mechanism of course the two bolts so the first thing i'm going to do is put the carburetor itself [Music] right here i'm going to do the linkages first then the fuel line then we'll be able to get the other pieces on there so this guy in here like that linkages first um then this spring on the other hole okay fuel line moving this clamp down all right he's on there all right so that's good so this guy and the two bolts [Applause] and then this gasket which is going to go right up there so let's put it right on the screws here and we're going to start pushing the uh you're going to start putting the screws through the carburetor itself and now we've got to slip this gasket and choke mechanism on behind it and then it all goes up guess what i forgot the breather hose it's a it's a bit of a jigsaw puzzle so let's try that again i think our bolts are started tighten these just a little bit don't have to go nuts all right she's back on choke plate is closed as it should be because the engine is cold so the chokes mechanism is doing okay we're gonna put our air cover on here an air filter turn our fuel on verify there's no visible leaks from underneath and then uh take it down and give it a shot try it [Applause] out [Music] well guys it's fully warmed up now i verified that the choke plate is indeed fully open and you can see it's running a lot smoother so i think we fixed this surging uh surging problem and we're ready to uh put this guy back in service i hope that's of help to you on how to solve your surging lawnmower even if it's not a honda if it's a briggs and stratton or whatever other brand it's fuel flow through the carburetor jet that is the the main issue when it's surging like that so feel good about having that resolved thanks for watching and i will look forward to seeing you on the next video bye

Channel: Buck's Small Engine DIY

Views: 89,313

Keywords: MTD, Murray, Honda, Briggs and Stratton, Briggs & Stratton, mower is surging, mower surges, mower races up and down, up and down, lawn mower runs bad, mower runs poorly, mower runs rough, lawnboy, craftsman, lawn mower, lawnmower, GVC160, GCV160

Id: azOiJzTatCc

Length: 15min 14sec (914 seconds)

Published: Fri May 07 2021